1. Field of the Invention
This invention relates to a vehicle back up alarm system having a first warning signal when a vehicle is shifted into a reverse gear and a second warning signal when the vehicle is moving in a reverse direction.
2. Description of Related Art
Accidents occurring from trucks and equipment backing into or over workers, laborers and pedestrians remain a problem even with the use of back up alarms that beep when trucks are shifted into reverse. Statistics show that 85 fatal accidents occur annually as a result of on-road back ups, and 390 fatal accidents occur annually as a result of off-road back ups. Further, an OSHA accident investigation database indicates that “an audible back up alarm installed by an original equipment manufacturer was ineffective in preventing an accident in two-thirds of the reported back-over accidents.”
In the construction industry, OSHA requires that all vehicles be equipped with a back up alarm (BUA) or that a human spotter be employed. Outside the construction field, there are no mandates for a BUA. Conventional BUAs transmit warning signals only when a reverse gear of the vehicle is engaged and continue to transmit the same warning signal while the reverse gear is engaged, whether the vehicle is stationary or moving. Therefore, there is no visual or audible change of the alarm once the vehicle moves, stops and/or moves again.
A conventional BUA system consists of an alarm and a transmission switch that allows current to flow to the alarm when the transmission switch closes, such as when the vehicle reverse gear is engaged. Upon disengagement of the reverse gear, the transmission switch opens, breaking the current flow to the alarm, thus disabling and silencing the alarm.
In order to reduce continuous or unneeded warning signals, which can lead to noise saturation and ultimately complacency, some conventional BUA designs use infrared scanners, sonar or Doppler radar to detect an object behind the vehicle. If an object, such as a person, is detected behind the vehicle, the alarm is activated to transmit a warning signal. However, these conventional BUAs do not communicate to bystanders that the vehicle is in motion. Further, conventional BUAs do not provide any warning signal to bystanders who do not have direct sight of the vehicle as the vehicle moves in the reverse direction.